Project Summary Pancreatic adenocarcinoma (PDAC) is a devastating disease characterized by high rates of metastasis and poor therapeutic response. It is currently the 4th leading cause of cancer related deaths in developed countries and despite efforts to improve therapy, the five-year survival rate remains at 9%. Therefore it is critical to identify new programs that drive pancreatic cancer progression and therapeutic resistance. To define new cancer dependencies, work in the Reya lab has focused on characterizing stem cell programs that drive cancer initiation, propagation, and relapse. Previously published studies have demonstrated that the fate determinant Musashi2 functionally marks a stem population in pancreatic cancer, and more recent work has revealed that this stem cell population is characterized by a highly unique transcriptional and epigenetic profile. Given the crucial role for epigenetic regulation in development and dysregulation in cancer, it is logical to hypothesize that differentially expressed epigenetic regulatory factors could be responsible for the establishment or maintenance of this unique stem cell state in pancreatic cancer. Using functional screens to profile the impact of inhibition of candidate epigenetic factors on stem cells in vitro, the gene Smarcd3 has been identified as a potential critical mediator of stem cell growth in pancreatic cancer. Smarcd3 encodes Baf60c, a component of the SWI/SNF nucleosome remodeling complex that is known to be dysregulated in pancreatic cancer. Preliminary studies have shown that Smarcd3 inhibition leads to reduced growth of KPf/fC pancreatic cancer stem cells in vitro and in vivo. Smarcd3 inhibition also leads to reduced anchorage-independent growth of human pancreatic cancer cell lines in vitro. Based on these data, the aims of this proposal are to test the hypotheses that (1) Smarcd3 is required for pancreatic cancer growth and stem cell expansion in genetically engineered mouse models, and (2) Smarcd3 is required for growth of human pancreatic cancer cell lines and patient-derived pancreatic cancer xenografts.